Dinosaur renaissance
Robert T. Bakker coined the term "dinosaur renaissance" in a 1975 Scientific American article.]] The "Dinosaur renaissance"The term has entered into common usage after an article of the same name by paleontologist Robert T. Bakker in Scientific American, in April 1975. Examples can be found here and here. was a small-scale scientific revolution started in the late 1960s, which led to renewed academic and popular interest in dinosaurs. It was sparked by new discoveries and research indicating that dinosaurs may have been active and warm-blooded animals, rather than cold-blooded and sluggish as had been the prevailing view and description during the first half of the twentieth century. The new view of dinosaurs was championed by John Ostrom, who argued that birds evolved from coelurosaurian dinosaurs,Ostrom, J. 1974. Archaeopteryx and the Origin of Flight. The Quarterly Review of Biology Vol. 49, No. 1 and particularly Robert Bakker who argued passionately that dinosaurs were warm-blooded in a way similar to modern mammals and birds.Bakker, R.T. 1986. The Dinosaur Heresies. William Morrow, New York. Bakker frequently portrayed his ideas as a renaissance of those popular in the late nineteenth century, referring to the period in between the wars as "the dinosaur doldrums". The dinosaur renaissance led to a profound shift in thinking on nearly all aspects of dinosaur biology, including physiology, evolution, behaviour, ecology and extinction. It has also lead to multiple depictions of dinosaurs in popular culture. Dinosaurs and the origin of birds '' (left) and Archaeopteryx (right) led John Ostrom to revive the link between dinosaurs and birds.]] In the mid and latter parts of the nineteenth century, many scientists thought there was a close relationship between birds and dinosaurs—and that dinosaurs represented an intermediate stage between "reptiles" and birds. It was shortly after the 1859 publication of Charles Darwin's The Origin of Species, British biologist and evolution-defender Thomas Henry Huxley proposed that birds were descendants of dinosaurs. He cited skeletal similarities, particularly among dinosaurs, the "first bird"—''Archaeopteryx—and modern birds.Huxley, T. H., 1868: On the Animals Which Are Most Nearly Intermediate between Birds and Reptiles ''Annals and Magazine of Natural History''Huxley, T. H., 1870: Further Evidence of the Affinity between the Dinosaurian Reptiles and Birds ''Quarterly Journal of the Geological Society, Scientific Memoirs III http://aleph0.clarku.edu/huxley/SM3/Dino-boid.html However, in 1926, Gerhard Heilmann wrote his influential book The Origin of Birds,Heilmann, G. 1926: The Origin of Birds. Witherby, London. ISBN 0-486-22784-7 (1972 Dover reprint) in which he dismissed the dinosaur-bird link, based on the dinosaurs' supposed lack of a furcula (fused clavicles).An assumption which is now known to have been incorrect. Thereafter, the accepted hypotheses was that birds evolved from 'crocodylomorph' and 'thecodont' ancestors, rather than dinosaurs. This removed dinosaurs from playing a central role in debates about the origin of living species, and may have contributed to the decline of academic interest in dinosaur evolution. This remained the situation until 1964, when John Ostrom discovered a small carnivorous dinosaur which he named Deinonychus antirrhopus,Ostrom, J. H. (1969) "Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana." Peabody Museum of Natural History Bulletin, 30: 1-165. a theropod whose skeletal resemblance to birds seemed unmistakable. This led Ostrom to argue that Huxley had been right, and that birds had indeed evolved from dinosaurs. Although it was Deinonychus that inspired Ostrom to connect birds with dinosaurs, very similar birdlike dinosaurs, such as Velociraptor had been known for many decades,Osborn, H.F. 1924a. Three new Theropoda, Protoceratops zone, central Mongolia. American Museum Novitates 144: 1-12. but no connection had been made. After Ostrom's discoveries, the idea that birds evolved from dinosaurs gained support among palaeontologists, and today it is almost universally accepted. Newer methods, such as cladistics, and the discovery of several feathered dinosaurs have helped confirm the relationship. The relationship between dinosaurs and birds has led to considerable interest in dinosaur — particularly theropod — phylogeny, which is now far better understood. Dinosaur monophyly Initially, dinosaurs were thought to be a monophyletic group, comprising animals with a common ancestor not shared by other reptiles. However, Harry Seeley disagreed with this interpretation, and split the Dinosauria into two orders, the Saurischia ("lizard-hipped") and the Ornithischia ("bird-hipped"), which were seen as members of the Archosauria with no special relationship to each other.Seeley H.G. 1887. On the classification of the fossil animals commonly named Dinosauria. Proc R Soc London, 43: 165-171.Seeley H.G. 1888. The classification of the Dinosauria. Rep Br Assoc Adv Sci, 1887: 698-699. As such, the Dinosauria was no longer seen as a scientific grouping, and "dinosaur" was reduced to being a popular term, without scientific meaning. This became the standard interpretation throughout much of the twentieth century.Romer A.S. 1956. Osteology of the Reptiles. Chicago: University Chicago. 772 p. This changed in 1974, when Bakker and Peter Galton published a paper in ''Nature, arguing that not only were dinosaurs a natural monophyletic group, but that they should be raised to the status of a new class, which would also contain birds.Bakker, R. T., Galton, P., 1974. Dinosaur monophyly and a new class of vertebrates. Nature 248:168-172. Although initially this revival of dinosaur monophyly was controversial,Charig A. 1976. Dinosaur monophyly and a new class of vertebrates: a critical review. In: BELLAIRS AA & COX B (Ed.), Morphology and Biology of Reptiles. Linnean Society Symposium 3: 65-104. the idea did gain acceptance, and since the rise of cladistic methodology, it has been nearly universally supported.Novas, F.E. 1996. Dinosaur monophyly. Journal of Vertebrate Paleontology 16: 723-741. The raising of the Dinosauria to class rank found less support, perhaps largely due to increasing use of phylogenetic taxonomy among vertebrate palaeontologists, in which ranks are entirely abandoned. Warm-bloodedness and activity levels ) by Charles R. Knight. Bakker pointed to such restorations to demonstrate that in the 19th century it was widely accepted that dinosaurs may have been active and agile animals.]] In a series of scientific papers, books, and popular articles in the 70s and 80s, beginning with his 1968 paper ''The superiority of dinosaurs, Bakker, R.T., 1968, The superiority of dinosaurs, Discovery, v. 3(2), p. 11-22 Robert Bakker argued strenuously that dinosaurs were warm-blooded and active animals, capable of sustained periods of high activity. In most of his writings Bakker framed his arguments as new evidence leading to a revival of ideas popular in the late 19th century, frequently referring to an ongoing dinosaur renaissance. He used a variety of anatomical and statistical arguments to defend his case,Bakker, R. T., 1986. The Return of the Dancing Dinosaurs, in Dinosaurs Past and Present, vol. I Edited by S. J. Czerkas and E. C. Olson, Natural History Museum of Los Angeles County, Los AngelesBakker, R. T. (1972). Anatomical and ecological evidence of endothermy in dinosaurs. Nature 238:81-85. the methodology of which was fiercely debated among scientists.R.D.K. Thomas and E.C. Olson (Ed.s), 1980. A Cold Look at the Warm-Blooded Dinosaurs These debates sparked interest in new methods for ascertaining the palaeobiology of extinct animals, such as bone histology, which have been successfully applied to determining the growth-rates of many dinosaurs. Today, it is generally thought that many or perhaps all dinosaurs had higher metabolic rates than living reptiles, but also that the situation is more complex and varied than Bakker originally proposed. For example, while smaller dinosaurs may have been true endotherms, the larger forms could have been inertial homeotherms,Benton, M.J. (2005). Vertebrate Palaeontology. Oxford, 221-223.Paladino, F.V., O'Connor, M.P., and Spotila, J.R., 1990. Metabolism of leatherback turtles, gigantothermy, and thermoregulation of dinosaurs. Nature 344, 858-860 doi:10.1038/344858a0 or many dinosaurs could have had intermediate metabolic rates.Barrick, R.E., Showers. W.J., Fischer, A.G. 1996. Comparison of Thermoregulation of Four Ornithischian Dinosaurs and a Varanid Lizard from the Cretaceous Two Medicine Formation: Evidence from Oxygen Isotopes Palaios, 11:4 295-305 doi:10.2307/3515240 New theories on dinosaur behavior The late 60s onwards also saw several new theories on the way dinosaurs behaved. On the basis of trackways, Bakker argued that sauropod dinosaurs moved in structured herds, with the adults surrounding the juveniles in a protective ring.Bakker R.T. 1968. The superiority of dinosaurs. Discovery 3: 11-2 However, shortly afterwards this particular interpretation was challenged by OstromOstrom, J.H. 1972. Were some dinosaurs gregarious? Palaeogeography 11: 287-301 among others, although the venerable dinosaur track expert Roland T. Bird apparently agreed with Bakker.Bird, R.T. 1985 Bones for Barnum Brown. Fort Worth: Texas Christian University Press The first rigorous study of dinosaur nesting behaviour came in the late 70s, when palaeontologist Jack Horner showed that the duckbilled dinosaur Maiasaura cared for its young.Horner J.R., Makela R., 1979. Nest of Juveniles Provides Evidence of Family-Structure Among Dinosaurs, Nature 282 (5736): 296-298 Changing portrayal of dinosaurs The dinosaur renaissance changed not only scientific ideas about dinosaurs, but also their portrayal by artists. Bakker, himself a talented artist, often illustrated his ideas in a lively fashion. Indeed, Bakker's illustration of Deinonychus, made for Ostrom's 1969 description, has become one of the most recognisable and iconic of dinosaur restorations.It is now known that the drawing is inaccurate in many respects, including the pubis being far too short, and the fact that feathers are lacking. During the 70s, restorations of dinosaurs shifted from being lizard-like, to being more mammal- and bird-like. Artists started to show dinosaurs in more active poses, and incorporating newer theories of dinosaur locomotion and behaviour. Besides Bakker, key artists in this "new wave" were first Ely Kish, Mark Hallett, Gregory S. Paul in the 1970s, and during the 1980s Doug Henderson and John Gurche. Gregory Paul in particular defended and expanded on Bakker's ideas on dinosaur anatomy. He expounded a rigorous and detailed approach to dinosaur restoration, in which he often criticised the errors of the traditionalist approach.Paul, G. S., 1986. The science and Art of Restoring the Life Appearance of Dinosaurs and Their Relatives; a Rigorous How-to Guide, in Dinosaurs Past and Present, vol. II Edited by S. J. Czerkas and E. C. Olson, Natural History Museum of Los Angeles County, Los Angeles He also produced a large number of restorations showing small dinosaurs with feathers, and defended the idea in a number of articles and his book Predatory Dinosaurs of the World.Paul, G.S. 1988. Predatory Dinosaurs of the World. New York: Simon & Schuster. 464pp. His view was proven largely correct in the late 90s with the discovery of several feathered dinosaurs. Paul's ideas and style have had a significant impact on dinosaur art, and likely will continue to do so for some time. New extinction theories, the meteor impact Another factor contributing to the interest in dinosaurs was the acceptance and popularization of the idea, first proposed by Eugene Merle Shoemaker, that the Earth and other planets in the solar system are constantly bombarded by meteorites. This again led to the theory that the Cretaceous-Tertiary extinction event, which led to the disappearance of the dinosaurs 65 million years ago, was caused by a meteor impact, possibly the one that caused the Chicxulub Crater. This fever reached its height in 1994, when the Comet Shoemaker-Levy 9 hit Jupiter, with millions following the event live on television. Cultural impacts The dinosaur renaissance has been cited as the cause of renewed public interest in dinosaurs. Bakker's non-technical articles and books, particularly The Dinosaur Heresies, have contributed significantly to the popularization of dinosaur science. Notes and references Further reading * Bakker, R.T. 1986. The Dinosaur Heresies. William Morrow, New York. * Paul, G.S. 1988. Predatory Dinosaurs of the World. New York: Simon & Schuster. 464pp. * Czerkas, S. J. and Olson, E. C. (Ed.s) 1986. ''Dinosaurs Past and Present, Volumes I and II ''. Natural History Museum of Los Angeles County, Los Angeles. External links Artists: *John Gurche *Mark Hallett *Gregory Paul Renaissance Category:History of paleontology